This invention relates to apparatus for locating the position of a magnetic member relative to a nonmagnetic member, and in particular to such apparatus which is both portable and may be suitably employed in relatively confined spaces.
There are many applications in which it is extremely important to accurately fix the position of a magnetic member relative to a nonmagnetic member. For example, heat exchange apparatus typically includes nonmagnetic heat exchanger tubes extending between and supported by magnetic tube support sheets. The tubes are very often mechanically expanded into contact with the holes of the support sheet to firmly connect the outer surface of the tube to the inner surface of the hole of the support sheet. Mechanical expanders are employed to expand the tubes in the desired manner. In order to prevent damage to the tubes and to insure that the desired mechanical bond between the tubes and the surrounding support sheet is properly formed, it is extremely desirable that exact location of the magnetic support sheet relative to the nonmagnetic tubes is accurately fixed.
As may be readily recognized, the exact position of the tube support sheets relative to the tube is difficult to obtain as the tubes and support sheet are located within the housing of the heat exchange apparatus. Thus, some suitable means must be employed to accurately locate the position of the support sheet relative to the tubes.
Various devices have heretofore been employed in an attempt to locate an otherwise inaccessible or hidden magnetic member relative to a nonmagnetic member. Such prior art devices are disclosed in U.S. Pat. Nos. 2,768,684; 3,017,621; and 3,649,450. While each of these patents disclose various means for achieving the desired end, none of the patents utilize the field generated by a permanent magnet for locating the position of the magnetic member relative to a nonmagnetic member. In addition, each of the prior art devices are relatively large making them unsuitable for use in relatively small spaces, as for example small diameter tubes.